A triangulation method or a circle intersection method, in which hyperbolas or circles are formed using two or more sound sensors as focuses or centers and an intersection point thereof is determined as the location of a point, is used to estimate location of a sound source by using a sound signal.
A sound sensor arrangement and a sound signal arrival time difference are used to estimate a location by using a sound signal, and representative techniques for this estimation include an angle of arrival (AoA) technique, a time of arrival (ToA) technique, a time difference of arrival (TDoA) technique, etc.
According to the AoA technique, a location is measured by measuring angles of arrival and arrival time differences of received sound signals. According to the ToA technique, a location is measured using information about a time at which a sound signal arrives at one reference sound sensor and times at which sound signals arrive at two or more sound sensors, and for this technique, time synchronization between the sound sensors is required, and an error caused by a multipath should be considered. According to the TDoA technique, a location is measured using a difference of times at which sound signals arrive at a plurality of sound sensors, and this technique enables long-distance measurement using time difference information.
According to the above-mentioned location estimation techniques, sound signals are detected to accurately determine the location of a sound source which has generated the sound signals. Here, according to the above-mentioned location estimation techniques, a difference of times of the sound signals is measured using the detected sound signals. Regarding the measurement of the time difference, time delays of the sound signals significantly affect the performance of location estimation. Various methods for estimating time delays of sound signals have been proposed, but are limited in terms of the accuracy of time delay estimation.